First Oda has to show us the process to forge it, it's a EOS Zoro material so we won't see it soon. If it's a EOS Zoro material then something special is required to have a kokuto, the Elbaph Zoro is already a strong character with adCoc ( Harald or Xebec had adCoc but still no Kokuto). Roger named his son after his sword, so he had a special connection with that sword, you can't tell me they don't care about swords/swordmanship if they call their children with a sword name lmao. I don't know but if only two characters have it, there must be a reason, no? Ryuma has been compared to Joyboy, so I don't think it's a fraud and Mihawk is the first subordinate with a higher bounty than his captain ( a yonko) only because he is the strongest swordsman in the world. We are talking about top tiers like Rocks/Shanks/Roger, so I'm 100% sure you need something more to have a Kokuto.
Sorry for the long read lmao